'trace(Z) is valid only if the elements along the diagonal have the same curvature'

[xcc (xucheng)]

What’s the meaning of ‘trace(Z) is valid only if the elements along the diagonal have the same curvature’ in The CVX Users’ Guide?

[mcg (Michael C. Grant)]

It means that you can’t take the trace of a matrix whose diagonal has a mixture of convex and concave elements. It’s basically a straightforward application of the fact that trace(Z) = sum(diag(Z)).

[xcc (xucheng)]

Ok! Get it,Thanks:smile: